Couchbase Query Help

Hi,
Currently I have created the following index in the bucket:

CREATE INDEX index_one ON mt_bucket('a','b','c','d','e','f','g','h','i','type') USING GSI

if I am using the following N1Q1 query:

select * from mt_bucket USE INDEX (index_one USING GSI) where type=1 and a='a' and b='b' and c='c' and d='d' and e='e' and f='f' and g='g' and h='h' and i='i'
CouchBase Server Query Response time is millisecond.

However For the Following Query, it takes a minute

select * from mt_bucket USE INDEX (index_one USING GSI) where type=1 and a in ['a1','a2','a3','a4'] and b in ['b1','b2','b3','b4'] and c='c' and d='d' and e='e' and f='f' and g='g' and h='h' and i='i'

What Should I do to optimize the query